782
FXHW60 PHFO 031810
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
810 AM HST SAT OCT 3 2026
SYNOPSIS
LIMITED SHOWERS WINDWARD AND MAUKA INTO NEXT WEEK. MORE WIDESPREAD
RAIN DEVELOPS OVER THE WESTERN END OF THE STATE BY WEDNESDAY.
PERIODS OF HEAVY RAIN WILL BE POSSIBLE OVER AND AROUND KAUAI AND
POTENTIALLY OAHU.
SHORT TERM UPDATE
PROLONGED PERIOD OF MOIST SE FLOW HAS COME TO AN END AND BENIGN
MODERATE TO BREEZY TRADES CONTINUE THROUGH TUESDAY. WINDS WILL PERK
UP SUNDAY INTO EARLY MONDAY AS A WEAK TROPICAL DISTURBANCE ADVANCES
WESTWARD SOUTH OF THE AREA. HOWEVER, NOTHING MORE THAN A MODEST
COVERAGE OF WINDWARD AND MAUKA SHOWERS IS EXPECTED. NO UPDATES
NEEDED IN THE NEAR TERM.
ATTENTION FOR MID-WEEK TURNS TO A QUICK PATTERN TRANSITION FROM
ACTIVE TROPICS TO A VERY EARLY WET SEASON TYPE OF SYSTEM. A DEEP
LONGWAVE TROUGH EXTENDING FROM THE MID-LATITUDES INTO THE SUBTROIPCS
IS MODELED TO DEVELOP DURING THE FIRST HALF OF THE WEEK. DEEP LAYER
FLOW VEERS TO THE S/SE IN ADVANCE OF THIS TROUGH DRAWING DEEP
TROPICAL MOISTURE NORTHWARD AS EARLY AS WEDNESDAY. A SURFACE LOW
WILL DEVELOP AROUND 30N LATITUDE NORTHWEST OF KAUAI WITH THE WESTERN
HALF OF THE ISLAND CHAIN MOST LIKELY TO RECIEVE MEANINGFUL RAINFALL.
WHILE GUIDANCE VARIES ON IMPORTANT DETAILS, SUCH AS THE POSITION OF
THE DEVELOPING CLOSED LOW AND HOW LONG IT PERSISTS, THE END RESULT
SEEMS TO BE AN EMERGING THREAT FOR HEAVY RAIN AND FLASH FLOODING ONE
WAY OR ANOTHER DURING THE SECOND HALF OF THE UPCOMING WEEK. THE GFS
ALLOWS TRADES TO BUILD IN CONSIDERABLY FASTER, SEEMINGLY IN RESPONSE
TO ITS DEVELOPMENT OF A SUSPICIOUSLY COMPACT AND INTENSE SURFACE LOW
WHICH QUICKLY OCCLUDES AND WRAPS WESTWARD UNDER THE UPPER LOW. THE
EC APPEARS MORE REALISTIC AT THIS TIME AND FAVORS A FLOODING THREAT
THAT COULD PERSIST FOR A FEW DAYS OVER KAUAI AND POTENTIALLY OAHU.
FORECAST SOUNDINGS SUGGEST THAT WHILE THE DRY SLOT WILL LIKELY
BECOME ESTABLISHED WEST OF THE ISLANDS, DRY AIR ENTRAINMENT WITHIN
MID-LEVEL SW FLOW MAY STILL BE A LIMITING FACTOR, ESPECIALLY WITH
RESPECT TO OVERALL COVERAGE OF DEEPER CONVECTION. THIS SYSTEM WILL
BE A FOCUS OF THE AFTERNOON FORECAST PACKAGE.
AVIATION
TRADE WIND PATTERN WILL CONTINUE TODAY, WITH ISOLATED MORNING
SHOWERS OBSERVED ON A COUPLE WINDWARD AND MOUNTAIN AREAS, WITH
THE MOST LIKELY MVFR CONDITIONS AT THE LIHUI AND HILO TERMINALS
THROUGH MORNING. OTHERWISE, VFR CONDITIONS SHOULD PREVAIL THE
REST OF THE DAY.
NO AIRMETS IN EFFECT.
MARINE
GENTLE TO FRESH NORTHEAST TO EAST TRADE WINDS HAS FILLED IN
TODAY AS HIGH PRESSURE STRENGTHENS GRADUALLY TO THE NORTH. A
SMALL CRAFT ADVISORY HAS BEEN ISSUED, IN EFFECT BEGINNING THIS
EVENING, WHEN LOCALLY STRONG TRADES ARE FORECAST TO DEVELOP FOR
THE WINDIER WATERS AND CHANNELS AROUND MAUI COUNTY AND THE BIG
ISLAND. LOCALLY STRONG TRADES MAY PERSIST INTO EARLY NEXT WEEK
BEFORE HIGH PRESSURE TO THE NORTH WEAKENS AGAIN AND WINDS START TO
DIMINISH. BY THE MIDDLE OF NEXT WEEK, TROUGHING DEVELOPING
NORTHWEST OF THE ISLANDS MAY CAUSE WINDS TO VEER OUT OF THE
SOUTHEAST ONCE AGAIN.
A SMALL BACKGROUND SOUTH SWELL WILL SURF MOSTLY STEADY ALONG SOUTH
FACING SHORES THROUGH THE WEEKEND. A NEW SMALL, LONG-PERIOD SOUTH
SWELL, ORIGINATING FROM A LARGE FETCH OF GALE FORCE WINDS SOUTHEAST OF
NEW ZEALAND EARLIER THIS WEEK, IS FORECAST TO ARRIVE BEGINNING SUNDAY
AND PEAK MONDAY THROUGH WEDNESDAY. THIS WILL PUSH SURF TO SLIGHTLY
ABOVE SEASONAL AVERAGES FOR THE FIRST HALF OF NEXT WEEK.
A SMALL BUMP IN SURF ALONG NORTH-FACING SHORES WILL DECREASE TODAY AS
A SMALL, SHORT PERIOD NORTH SWELL FADES. ANOTHER SMALL BUMP IN NORTH
SHORE SURF IS POSSIBLE EARLY NEXT WEEK AS A SMALL, MEDIUM-PERIOD
NORTHWEST SWELL ARRIVES LATE SUNDAY AND PEAKS ON MONDAY. THIS WILL BE
FOLLOWED BY A SLIGHTLY LARGER LONG-PERIOD NORTHWEST SWELL PEAKING ON
WEDNESDAY, GIVING A GOOD BOOST TO NORTH SHORE SURF FOR MID-WEEK. SURF
ALONG EAST FACING SHORES WILL INCREASE AND BECOME MORE CHOPPY THROUGH
TONIGHT AS EASTERLY TRADES BUILD BACK INTO THE REGION.
FIRE WEATHER
ISSUED AT 328 AM HST SAT OCT 3 2026
DRIER AIR IS EXPECTED OVER THE WEEKEND AS LIGHT TO MODERATE
EAST- NORTHEASTERLY TRADES RETURN. WINDS ARE EXPECTED TO DECREASE
EARLY TO MIDWEEK. ISOLATED SHOWERS WILL FAVOR WINDWARD AND MAUKA
AREAS OVERNIGHT INTO THE EARLY MORNING HOURS. FIRE WEATHER
CONDITIONS WILL REMAIN BELOW CRITICAL THRESHOLD THIS WEEK FOR BOTH
WIND AND HUMIDITY LEVELS. TEMPERATURE INVERSION HEIGHTS ARE AROUND
5000-7000FT.
HFO WATCHES/WARNINGS/ADVISORIES
SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 6 PM HST SUNDAY
FOR ALENUIHAHA CHANNEL-BIG ISLAND LEEWARD WATERS-BIG ISLAND
SOUTHEAST WATERS-MAALAEA BAY-PAILOLO CHANNEL.
SHORT TERM UPDATE...JVC
AVIATION...PECHACEK
MARINE...SHIGESATO
FIRE WEATHER...WALSH
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